One of the Concorde's four engines may have burst under the strain of takeoff, taking out a second engine and precipitating a low-altitude stall from which the jetliner could not easily recover, said two aviation experts who were studying yesterday's crash near Paris.

"The failure of a single engine wouldn't cause loss of control, but the failure of two could," said Barry Schiff, a retired TWA pilot and aviation safety consultant. "The delta wing on that plane is very unforgiving at takeoff speeds."

"Theoretically, the plane would still have been able to fly," said Glen Shoop, a retired Concorde pilot. "But in that situation, it would have been very difficult to control."

Schiff and Shoop said their theories about the crash of Air France Flight 4590 are only speculation -- based largely on their experience, the reports of a professional pilot who watched the crash and a photograph showing flames trailing from at least one of the jet's engines.

The official determination of the cause -- based on the study of radar data, debris, witness reports, maintenance records and on-board recordings that officials have recovered from the wreckage -- probably won't be made for a year or more.

The Concorde's four Rolls-Royce engines, each developing about 38,000 pounds of thrust, were at full power as the sleek supersonic jet took off from Paris' Charles de Gaulle airport shortly after 4:30 p.m. local time yesterday.

Engineers said it is at just such a moment, when jet engines are producing maximum thrust, that they are most likely to break down.

Witnesses on the ground, backed up by a dramatic color photograph taken by a tourist, described a 100- foot plume of fire streaming back from the engine area on the left wing as the jetliner struggled into the air.

"In almost every case, it's the worst possible time and the worst possible set of circumstances for an airline crew to deal with," said David Thomas, a former head of accident investigation for the Federal Aviation Administration.

Schiff said the Concorde has pairs of engines on each side of the fuselage, "and the engines in each pair are very close to each other, side by side. If a turbine burst on one of those engines, it could take out the other one."

"When one of those engines comes apart, it can throw pieces everywhere," Shoop said.

Witnesses said the plane appeared to stall, pitching up steeply into a nose-high attitude before falling off to one side and crashing near a hotel in the town of Gonesse, about nine miles northeast of Paris.

A stall occurs when the smooth flow of air over a wing is interrupted, depriving the wing of lift.

Schiff said the plane's delta- shaped wing design -- unique to the Concorde among the world's commercial jetliners -- makes supersonic flight possible, but it also makes recovery from a low-altitude, low-speed stall especially difficult.

Although yesterday's crash was the first involving the Concorde, the plane has suffered mechanical problems in the past. Since 1989, three of the jetliners have lost large sections of their tail rudders in flight, but all three landed safely.